Did you check the road closures on the website and the table listing all the opening dates for the roads that close in winter?

Of course, this year, Tioga may not open even if the snow melts by then. Glacier Point Road and Tioga Road are typically plowed and obstructions cleared before they allow traffic on them. Sequester may have delayed such activity, so it may still be May before they open.

Hetch Hetchy road is closed indefinitely due to a slide. The other roads, 120, 140, and 41, are all open, and Mariposa Grove will be open then as well.